Automatic telephone system



Jan. 11, 1927. 4,441

W. T. POWELL AUTOMATI C TELEPHONE SYSTEM Filed Jan. 16. 1922 2 Sheets-Sheet l GENERATOR.

CONNECTOR NOTEi-X CONTACT CLO5ES BEFORE Y CONTACT OPENS.

SELECTOR.

INVENTOR HOPPHUMEIUCAL BY W ATTORNEY WINFRED T OWELL.

INVENTOR WIHFRED T. POWELL.

n! t e e h S v s h t p e m WW S M 2 M E T ma L 9 L 5 w P OE. P.&n .T T J C d VI. e WA 1v T U w MAW MOFUMZ Z0 0 Jan. 11 1927.

ATTORNEY Patented Jan. 11, 1927.

UNITED STATES PATENT OFFECE.

WINFRED T. POWELL, OF ROCHESTER, NEW YORK, A$SIGNOR TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY. OF ROCHESTER, NEW YORK, A

CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE SYSTEM.

Application filed January 16, 1922.

This invention relates to telephone sysems and more particularly to telephone systems employing automatic switches in completing telephone connections.

In former telephone systems the directively operated magnets of the numerical switches have been controlled at contacts of impulse relays operated over the two sides of the line in series, with the result that on long telephone lines the impulse relay is only weakly operated so that a complete impulse is not transmitted to the operating magnet. This resulted in improper operation of the numerical switches and the consequent error in connections.

The purpose of the present invention is to provide an arrangement in which the dircctively operated magnets of the numerical switches will be positively operated irrespective ot' the length of telephone lines over which they are controlled.

The main feature of the present invention is the use of inductive means for repeating impulses to the directively operated magnets of non-numerical switches. Other features of the invention include the detailed circuits by which such operation is achieved, all of which will be brought out in the detailed description and the appended claims.

In the drawings Fig. 1 represents a telephone system including the present invention.. The portion of the drawing at the left of the dotted line represents the calling telephone line and the circuits of a selector switch; at the right of the dotted line there is diagrammatically represented the circuits of a connector switch and 21 called telephone line. The connector in Fig. 1 is of that type known in the art as a side switchless connector.

Fig 2 represents a modified form of the invention applied to a connector switch circuit ot' the type known in the art as, a connector switch with side-switch.

The mechanical structure of the selector switch herein referred to may be of the type disclosed in the .patent to Keith, Erickson and Erickson #815,321 issued March 13, 1906, while the mechanical structure of the connector switch may be similar to the patent to Keith, Erickson and Erickson #815,176, patented March 13, 1906. It will Serial No. 529,542.

be understood, of course, that it this type of connector is employed in the circuits of Fig, 1 the side switch may be omitted.

It is believed that the invention will best be understood by describing the method of establishing a telephone connection from a subscriber at the sub-station, indicated at A to a subscriber whose substation 'is indicated at B.

When the subscriber at A removes his receiver from its switch hook, a non-numerical switch of any well known type operates to extend the calling line to an idle trunk which leads to an idle selector switch. Let it be assumed that the non-numerical switch' seizes the trunk, whose conductors 5 and 6 lead to the selector switch of Fig. 1. As soon as this switch is seized, its impulse relay 7 will be energized from grounded battery, through its right hand winding, uppermost back contact and armature of cutthrough relay 8, over the upper side of the established connection, including conductor 5, through the substation circuits at A, over the lower side of this connection including conductor 6, inner armature and back contact of relay 8, left hand winding of relay 7 to ground. The relay 7 is energized in this circuit and at its armature and front contact completes a circuit for operating the slow releasing relay 9 and completes a circuit in multiple therewith for the relay 10, which circuit is traced from grounded battery, left hand winding of the relay 10, front contact and armature of relay 7, lowermost back contact and armature of relay 8 to ground. The relay 10 is energized in this circuit, but its right hand winding, which is inductively connected with the left hand winding, is short circuited at its armature and back contact. of relay 10, however, its armature is attracted so that when it deenergizes, a current is induced in the right hand winding of this relay which operates the relay 11, as will be described. At the left hand armature and contact of relay 9, the circuit for the release magnet 12 is opened, thereby preventing the release of the selector switch at this time. At the right hand armature and front contact of relay 9, ground is applied to conductor 13 which serves to pre- (ill On the energization vent, temporarily, the release of the nonnumerical switch as will be understood from this description.

In response to the series of impulses corresponding to the first digit of the wanted number, relay 7 vibrates its'armature once for each impulse. At the retraction of the armature of relay 7, the energizing circuit of the relay 10 will be interrupted causing a curre t to be induced in the closed circuit including the right hand winding of relay 10 and the winding of relay 11. This will operate relay 11 and thereby complete an operating circuit for the primary motor n'zagnet l i, from grounded battery, winding of this magnet, slow releasing change-over relay 15, armature and front contact of relay 11, lowermost back contact and armatu're of relay 8 to ground. it each completion of this circuit of the primary motor magnet, it advances the brushes 16, and 18 of the selector in their primary direction to select a group of trunks through which the called line may be reached. At the termination of this series of impulses, the impulse relay 7 maintains its armature attracted for a relatively long interval, thereby permitting the change-over relay 15 to decnergize. The relay 19 has been maintained energized in a circuit completed from grounded battery winding of this relay, off normal contacts 20, armature and continuity spring of relay 15, conductor 13, armature and front contact of relay 9 to ground. Thus, when tl e slow releasing change-over relay 15 deenergizes, a circuit is closed from grounded battery, winding of the secondary magnet 21, inner front contactand armature of relay 19,'baclr contact and continuity spring of relay 15, armature and front contact of relay 9 to groom... Under the control of this circuit the secondary motor ma net 21, advances the brushes 16, 17 and .18 or the selector switch into engagement with the first trunk'of the selected group. Let itbc assumed that this trunk is busy when it is thus tested by the test brush 18, which busy condition will be ini'l cated by the presence of ground potent ial. on its test terminal, applied at the left hand front contact and ar rature of the relay corresponding to 22, associated with the busy trunk. hen the test brush 18 engages thisbusy trunk a circuit willbe closed from ground, the test terminal of the busy trunk, test brush 18, armature and back contact of relay 8, conductor .43, armature and back contact of the secondary motor magnet 21, of normal contacts 20, winding of relay 19 to grounded battery.

At this time a circuit is closed for the relay 8 which is ineffective to operate this re lay at this time. T his circuit extends from grounded battery, winding of relay 19, oil normal contact 20, back contact and armature of magnet 21, conductor 23, winding of relay 8, conductor 13, armature and front contact of relay 9 to ground. It will be noted that this circuit is ineffective to operate relay 8 while the test brush 18 is encountering busy test terminals which are characterized bythe presence of ground potential. lVith the relay 1%), operated over the circuit last described, the energizing circuit for the in'agnet 21 will be closed from ounded ljx-attery, winding of this im'ignet, inner contact and armature of relay 19, back contact and continuity spring of relay 15, rmature and front contact of relay 9 to ground. The secondary motor magnet 21 is operated in this circuit and advances the selector switch brushes into engagement with the next trunk of the selector group. lVhen the secondary motor magnet 21 operates it opens the: circuit of relay 19 causing it to dcenergize. If, however, the trunk which is now beingtested by the test brush 18 is busy, the relay 19 will again be operated to cause another operation of the secondary motor magne" 21 and the consequent advancement of the selector switch brushes. It will thus be seen that the relay 19 on energization closes an operating circuit for the motor magnet 21, and this magnet when it operates opens the energizing circuit of the relay 19 to effect its deenergization and this relay will only operate again, if the test brush 18 is still in engagement with the test terminal .of a busy trunk.

Let it be assun'iedthat the first idle trunk tested by the test brush 18 is that repre sented in Fig. 1, the test terminal 24,- of which is characterized by the absence of pr tential thereon, due to the fact that its associated relay is not operated. The relay 8 will no longer be short circuited but will be operated in the circuit previous1 described. Atthe upper armaturcs and back contacts of relay 8, the impulse relay 7 of the selector is removed from the control of the calling line and the conductors and 6 of the first so ector trunk are e:-;tended to the brushes 16 and 17 of the selector switch. The impulse relay 25 of the connector switch will thereupon be energized in the circuit extending-from grounded battery, left hand winding this relay bacl; contact and continuity spring of relay 26 over the upper side of the connection. thus far established through the sub-station A, over the lower side of the connection including conductor (5 and selector brush 17, continuity s1 ring and back contact of rela 26, right hand winding of 25 to ground. Relay is energized in this circuit and at its front contact and armature completes an energizing circuit for the slow releasing relay 22. This last mentioned relay attracts its armatures and at its left hand armature and front contact applies ground potential to the test terminal 2 1 of the last selected ion - contact of magnet 21, off normal contacts 20, winding of relay 19 to grounded bat- I tery. Relays 19 and 8 are so designed that the relay 8 will be energized in this circuit, but the relay 19 will remain inactive.

When relay attracted its armature, it closed an operating circuit for the relay 27 inmultiple with that of the relay 22; This circuit is traceable from. ground, armature and frontcontact of relay 25, left hand winding of relay 27 to grounded battery. The relay 27 is energized in this circuit and induces a current in its right hand winding, but thiscurrent is ineii'ective to operate the relay 28 because the right hand winding of relay 27 is short circuited at its armature and b ack contact. lVhen, however, the relay 27 is energized the short circuit is removed from the right hand winding of relay 27 and this winding will be effective to operate the relay 28 for purposes to be fur ther described.

The apparatus and circuits of the connector switch are now in condition to receive the series of impulses corresponding to the tens digit of the wanted number. The sub scriber at A now operates his dial sender to transmit the tens series of impulses and in response to each of these impulses, the impulse relay 25 retracts its armature. This, however, will be inefiective to cause the operation of the release magnet 29 because its circuit is now open at the outer armature and back contact of relay .22. lVhen the relay 25 thus retracts its armature it opens the energizing circuit of the relay 27 and, as has been described, this relay deenergizes and induces a current in its right hand winding to cause the energization of relay 28. This relay closes a circuit from ground, armature and front contact of relay 28, oil normal contact springs 30 and 31, winding of the change-over relay 33, winding of the primary motor magnet 34': to grounded battery. Theslow releasing relay 3% is energized in this circuit and at its armature and back contact holds open the operating circuit oi" the secondary motor magnet 35 of the connector switch. The primary magnet 34;, therefore, is operated in this circuit and advances the brushes 36, 37 and 38 otthe connector switch one step in its primary movement. This is effective to open the oil-normal contacts 30 and 31 but contact springs 30 and are closed before this takes place, since the contact springs 30, 31 and 32 are of the make-before break arrangement. In response to the remainder of the tens series of impulsesf the relay 28 will be operated in the manner already described, to close intermittently an operating circuit for the primary motor magnet 23% from grounded battery, winding of this magnet, winding, front contact and armature of the change-over relay 33, offnormal contacts 30 and 32, from contact and armature of relay 28 to ground. The primary motor magnet will continue to operate in this circuit until the connector switch brushes are placed in operative position to the group of lines including the wanted telephone line. At the close of this series of impulses, the impulse relay 25 will maintain its armature attracted for a relatively long interval so that no impulse will be inductively transmitted to the relay 28, consequently the operating circuit of the relay 33 will be open for a relatively long period causing this relay to deenergize. The connector is now in condition to receive the series of impulses corresponding to the units digit of the wanted number.

The subscriber at A now operates his dial sender to send this series of impulses and in response to each impulse the operating circuit of the relay 27 is opened and this relay induces an impulse of current in the winding of relay 28. This last mentioned relay, thereupon, attracts its armature to close a circuit from ground through contacts and 32, armature and licir contact of the changeover relay 83, inner back contact and armature of relay 39, armature 40, of relay ell, winding of the secondary motor uagnet 35 to grounded battery. This secoudaryinotor magnet actuated in this circult and advances the set of brushes one stcp in their secondary direction.

On thelirst operation of the relay 28 and in response to the first units impulse the slow releasing relay 42 will be energized in multiple with the secondary magnet and this relay when operated, closes a locking circuit for itself, through its lelt hand ront contact and armature. In response to each of the units impulses the secondary motor magnet advanccs the connector switch brushes until at the close of this series 01"? impulses the brushes 36, 37 and 38 of the connector will be in operative engagement with the terminals of the wanted line leading to substation At this time the operating circuit of relay, will be maintained open for 1 a relatively long period, so that this relay will deenergizc. i

Let it first be assumed that the wanted line idle at this time, whereupon a circuit is closed from grounded battery, winding of the cut-off relay d3 of this line, its test ter minal 50, test brush 3?, right hand armature and back contact of relay 42, upper winding of relay 4-1, back contact and armature of relay 39, conductor H, front contact and armature of relay 22 to ground. Relay 41 is operated in this circuit and closes a locking circuit for itself from grounded battery, through its lower winding, innermost lower front contact and armature, conductor 45, inner front contact and armature of relay 2 2 to ground. Relay ll when operated also closes its upper front contacts and armatures, thereby closing a ringing circuit extending from the ringing generator (not shown) conductor 46, inner bac contact and p cu .gized and will attract its armatures.

armature ot' the trip relay ll", inner upper front contactand armature of relay 4:], connector brush 37, through the substation circuits, over the uppcrside of the called line, connector brush 36, uppermost arn'iature and front contact of relay 4L1, upperinost arm-a ture and back contact of relay 4-7, upper winding of the trip relay 4? to grounded battery, Over this circuit ringing current is applied to the called line until the subscriber at suliistantion B removes his receiver from its switch hook, at which time the relay 4'7 will receive sufiicient current to be ener- Atthe upper armatures of relay t? a talking connection is completed and at the inner lower armature and contact of relay 4H, a locking circuit is completed for this relay through its lower winding, conductor l5, front contact and armature of relay 22 to ground. At this time a circuit is closed for relay 26 extending from grounded battery, left hand winding of this relay, over the upper side of the connection to the called line, and its substation circuits in series, over the lower side of the established connection, right hand winding of relay 26, inner lower front contact and armature of relay 4-7, conductor 45, inner front contact and armature of relay 22 to ground. The relay 26 attracts its arn'iatures and at its inner right hand armature and back contact opens a second break point in the circuit of the release magnet 29 for a purpose which will be later described. At the left hand armatures and continuity springs of relay 26, battery isreversed in the call ing side of the. connection to operate a call registering device or for other purposes incident to the operation of an automatic exchange. At the outer right hand arniature and front contact of relay 26 it e:;- tends conductor through the lowermost i'ront contact and armature of relay 47, contact 49 and armature or relay ii to ground, so that the holding circuit for relays 26, 41 and 47 is maintained independent of the control of the calling subscriber.

Talking battery is supplied to the calling party through the windings of relay 25, while tallt'ing battery for the called subscriber is applied through the windings of relay 26.

Let it be assumed that the wanted line is busy at the time it is tested which conditween tion will be indicated by the presence of ground potential on its test terminal 50 applied thi 'ough a test brush similar to S8 of the connector switch which has previously seized this line through the front contact and armature similar to 51 of a relay similar to 41 to ground at the connector switch which has already seized this line. Therefore at the time of tjhetest, a circuit will be completed from this ground, test terminal 50, test brush 2-18, armature and continuity spring of relay 42, lowermost back contact and armature o't' relay ill, winding 03f test relay 39 to rounded battery. This lastinentioned rel is energized in this circuit and when rela 12 deenergizes it closesa locking circuit for relay 3.9 from grounded battery, its winding, lower 'uost armature and back contact of relay 1-1, continuity spring and backcontact of relay 4-2, right hand front contact and armature of relay 39, conductor A, left hand front contact and armature of relay to ground.

At the inner armature and back contact of relay 39 the operating circuit of the secondary n otor magnet 35 is interrupted to prevent its further operation in the event that the subscriber at" A should operate his dial sender to send additional impulses. At the outer arinat ue and front contact of relay 39 a source of busy tone current B Z is extended over conductor to the calling line to indicate to the subscriber at A that the wanted line is not available,

At the close of the conversation when the subscriber at Areplaces his receiver on his switch hook, the energizing circuit for the relay 25 will be opened and this relay will deenergize. Shortly after this the slow releasing relay 22 which is controlled by the relay 25 deenergizes. At the left hand armature and front contact of relay 22, the holding circuit for the relay 8 of the selector is opened and in the event that the wanted line was busy when tested, the locking circuit of test relay 39 is also opened at the lett hand armature and front contact of relay Under this condition the circuit of the release magnet 29 ot the connector switch, is closed at the outer armature and back contact of relay 22. The relay 8 thereupon deenergizes and a circuit is now closed for the release magnet 12 extending -from grounded battery, winding of this magnet, oil normal contacts 54, back contacts and armatures ot relays 9,7 and 8 to ground. The release magnet 12 is energized in this circuit and ett ects the release of the selector switch in the well known manner.

It will be noted at this time that the releasing of the connector switch is not etfected because the circuit of this release magnet 29 is held open at the inner armature and back contact of relay 26. The con nector switch under consideration is so arlfl l ranged that both the calling and called subscribers must have terminated the conversation by replacing their receivers on their respective switch books before it is released. When the called party terminates the conversation the relay 26 deenergizes and if the calling party has terminated the connection relay 22 will also be deenergized so that an operating circuit for the release magnet 29 of the connector switch will be closed from grounded battery, winding 01 this magnet, otl' normal contacts 55, back contact andarmature of relay 26, back contacts and armatures of relays 22 and 25 to ground. Magnet 29 is energized in this circuit to effect the release of the connector switch in the well known manner.

In the modified form of the invention shown in Fig. 2, the improved impulsing arrangement is shown in connection with a connector provided with a side switch. For purposes of this description, it be assumed that the calling line A has been extended through the non-numerical switch and the selector switch of Fig. 1 and that the selector switch is stopped with its brushes 16, 17 and 18 in engagement with the terminals 56, 57 and 94: of the trunk circuit individual to the connector switch of Fig. 2 through which the wanted line and its substation C may be reached.

Since the connection has been established through the calling line and the selector switch brushes16 and 17 in engagement with the terminals 56 and "07, the impulse relay 58 will be energized over the two sides of the extended connection in series, through both windings of this relay to ground and grounded battery respectively. The impulse relay 58 is energized in this circuit and closes an operating circuit for the relay 59 at its front contact and armature. The relay 59 attracts its armature and at its front contact extends ground potential to the test terminal 94 which serves to guard this trunk against intrusion and also completes a holding circuit for the relay 8 in the manner already described. At the back contact and armature of relay 59 a break point is opened in the circuit of the release magnet 60 to prevent the release of the connector switch. At the time when the relay 58 attracts its armature, it also closes an energizing circuit for the relay 61 in multiple with that of the relay 59. This circuit is completed from ground, armature and front contact of relay 58, upper winding of relay 61 to grounded battery. The lower winding of the relay 61 is inductively associated with the upper winding of this relay and on each energization and deenergization of the upper winding an impulse of current is induced in the lower winding of relay 61: It will be noted that at the time that relay 61 is energizer! tl'ierc will be a short cir uit about relay 62, including the armature and back contact of relay 61. When relay 61 is energized it attracts its armature and opens this short circuit so that when the relay 61 deenergizes the-impulse induced in the lower winding of this relay will actuate the relay 62.

The circuits of the connector switch are now in condition to receive the tens series of impulses and the subscriber at A operates his dial sender to send a series of impulses and causes the relay 58 to vibrate its armature in the well known manner. On each interruption it opens the circuit including the upper winding of the relay 61. This causes an induced impulse to actuate the relay 62 and attract its armature. This closes an operating circuit for the primary motor magnet 63 from grounded battery, winding of this magnet, side switch wiper 65 in its first position, front contact and armature of relay 62 toground. In response to each of these impulses the motor magnet 63 advances the brushes 67, 68 and 69 of the connector switch in their primary direction to select the group of lines including the wanted telephone line.

It will be noted that the slow releasing relay 70 is energized in multiple with the primary motor magnet 63 at this time and completes an energizing circuit for the escape magnet 71 of the side switch, which circuit is closed from grounded battery, resistance. winding of this magnet, continuity spring and armature of relay 70 to ground. The structure of the side switch is well known and need not be described here. It

is sufficient to say that at the close of the tens series of impulses the relay 70 deenergizes and opens the circuit of the escape magnet 'I'lwhich releases to move the side switch wipers into their second position.

The circuits are now in condition to receive the directive impulses corresponding tothe units digit of the wanted number. The subscriber at substation A operates his impulse sender to transmit a series of impulses corresponding to the units digit of the wanted number. In response to each. of these impulses the relay 58 will retract its armature and this will be efiective to induce an impulse to actuate the relay 62 in the manner already outlined. As soon as the relay 62 actuates its armature it closes a circuit for energizing the relay 70 and this in turn effects the energization of the escape magnet 71. At this time a circuit is closed "from ground. armature and front contact of relay 62. side switch wiper 65 in its second position, back contact and armature of relay 72, winding of the secondary motor inagnet64 to grounded battery.

In response to each of these impulses, on each dab cities of the armature of t e. .1 f," jii'iiiar magnet Meshes lit) brushes 67., (58 and 39 of the connector tch until these brie-hes are in ope 'atiie relation with the terminals 92, 73 and 74- of he wanted line. At the close of this series impulses when the connector switch brushes have thus been positioned, the armature of relay 62 will be retracted for a rela tively long period which will effect the de energization of the slow releasing relay 70. This last mentioned relay will cause the deenerc'ization of the escape magnet 71 which in turn moves the side switch wipers into their third position. provided the called line is idle. It will subsequently be dcscribed what takes place it this line is busy.

\Vith the s de switch wipers in their third position tne escape magnet is energized in a circuit ext-endingthrough side switch wiper Oi and back contact of release magnet 60 to ground. Ringing current is also suppl ed to the called line from the ringing machine generally designated 75. through resistance lamp 7% trip relay 77, side switch wiper 78, brush 6S, terminal 73. through the called siibstation circuits, over the upper side of the called line, terminal 99, connector brush (37. side switch wiper 79 in third position to E I'OILI1(l. Ringing current is applied over this circuit until the called subscriber responts by removing his receiver 'lrom its switch hool: at which time the trip relay 7. will receive sutlicient cu'rent to be energrg' :cd and will attract its armature. This will short circuit the escape n'izigrnct ll wh' 1 will decnergrize and move the side switch wipers to their fourth or tallring position.

'lalkingg current is supplied to the calling line through the windings of impulse relay 55% while talking bat ery is supplied to the called party through the windings of im pcdancc coil 80. '7

Let it he a (l that the called line s busy when the test brush 69 engages the test terminal 74:. it this time the escape magnet 71 will be energized and the side switch wipers will be in their second position. However, when slow releasing; relay 7 dccncrgizes the escape magnet will be held operated in a circuit now raceablc from vgrounded battery, its windi g, continuity spring and back contact of relay TO,

windin r ot test relay 72h continuity spring and back contact of this relay, conductor 82 side switch wiper S3 in its second position test brush 69, test terminal H and through the multiple terminal thereot' through the brush similar to 69 and a side switch wiper similar to 83 in its third and fourth positions to ground at the connector switch which has already seized the called line. The test relay 72 is energized in this circuit and closes a lockingcircuit for itself in series with the escape magnet '71. through continuity spring and back contact of relay 70, winding continuity spring and armature of relay 72 and oil normal contacts ill to ground. 1th the test relay 72 operated a source of busy tone current is transmitted 'r *7 l- 1 a Wm 1101.1 source 1) J ovci concuc 01 7. full ture and front contact of relay *2 to the calling line.

When the calling subscriber a A termin ates the connection by replacing: his receiver on its switch hool; the energizing circuit of the relay 58 will be interrupted causing this relay to decnergize and retract its armature. This will open the energizing circuit of the slow releasing relay 59 and shortly afterwa 'ds this relay also retracts its armature. At its armature and front contact it remover-z the holding ground which has been applied to the test terminal during the conversation, and this permits the release (it the selector switch of Fig. 1 in the manner already scribed. At the back contact and armal e of relay 59 an operating; circuit closed for the release magnet from ground, through oft normal contacts 86, winding of the release magnet 60 to grounded battery. The release magnet is operated in this circuit and effects the release (it the connector switch in the well known manner.

is claimed is:

1. u an automatic telephone systcnr an incoming" circuit, a plurality ot outgoing circuits, :2 nuincri 'al switch individual to sa d llilftinlllig circuit for connectiiur; said ng circuit to any of said outgoing cira motor magnet for said numerical S'Vilt(fii.-H1QEU'1S for transmitting in'ipulses over said incoming"; circuiti an impulse relay normally connected to said incomii'ig circuit anl responsive to impulses from said impulse transmittiiur means, a transformer relay energized in I'OHPUDHB to each iu'ipulsc trans mitted to said impulse relay. and means in ductircly connected to said transtornua relay and responsive to impulses tor ellcctiirn the opcr: tion of. the motor magnet oi said switch said inductively cminccte'l nunerica: means being controlled by conta trausforn'icr relay.

9. In a trlc 'ihone system. an inc cuit a pl 'ility ol' outgo ng circa l on said :omatic swit 2h ineividual to said u circuit or connect in said incoming circuit to of said or going: circuits. a mot r li'iil rtfor operating said automatic switch. npulse transmitting device for transmittinc impulses or er said incoming ircuit. an impulse relay normally connected to said it coming circuit and responsive to impulses tran itted from said impulse train-muting device" a transtorn'ier relay controlled by said impulse relay, a third relay normally short-'circuitcd by and indu tire y connected to said transforn'ier relay. said third relay being responsiveto inductive impulses repeated by said transformer relay, and a circuit for said motor magnet controlled by said third relay.

'3. in an automatic telephone system, an incoming circuit a plurality of oulgolng circuits, an automatic switch individual to said incoming circuit tor connecting said incoming circuit to any of said outgoing circuits, an impulse transmitting device for transmitting impulses over said incoming circuit, an impulse relay normally connected to said incoming circuit and responsive to impulses transmitted from said impulse transmitting device, a transtormer relay having a pluralityot windings, a circuit for said transformer relay including one of its windings and arranged to be completed at said impulse relay, a third relay, a normally shortcircuited circuit for said third relay including the winding thereof and another winding of said transformer relay, a motor magnet for operating said automatic switch, and a circuit for said magnet controlled at contacts of said third relay.

4;. In an automatic telephone system, an incoming line, a plurality of outgoing lines, an automatic switch individual to said incoming line for extending said incoming line to any of said outgoing lines. a motor magnet for operating said automatic switch, an im pulse relay normally connected to said incoming line, an impulse sender tor transmitting impulses over said incoming line to directively operate said impulse relay, a transformer relay controlled by said impulse relay, normally short-circuited electro-magnetic means inductively connected to said transformer relay, changeover mechanism for determining the operation of said motor magnet, and a circuit for said motor magnet controlled at said change-over mechanism and said electro-magnetic means.

In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for interconnecting said incoming circuit with any of said outgoing circuits. a primary motor magnet for operating said automatic switch in a primary direction, a secondary motor magnct tor operating said automatic switch in a scci'indary direction, a. in'ipulse relay norn'mlly connect ed to said incon'iing c'ircuii l said impulse relay being responsive to impulses transmitted over said incoi'ning circuit, a second relay operating in synchronism with said .inu'iulse rela electromagnetic means inductively connected to said second relay, change-over mechanism for terminatii'lg the opm'ation of said primary motor magnet and for preparing an operating circuit for the secondary motor magnet and subsequently disabling said last mentioned operating circuit, an operating circuit for the primary motor magnet controlled by said change-overdeviee and by said electromagnetic means, a test relay associated with said swltch tor preventing said switch trom seizing a wanted out-going circuit in the event that said circuit is busy and an operating circuit for the secondary motor magnet controlled by said test relay, by said change-over device and by said electromagnetic means.

6. In an automatic telephone system,;an incoming circuit, a plurality of outgoing circuits, an automatic switch for interconne'ting said incoming circuit with any of said outgoing circuits, a primary motor magnet for operating said automatic switch, an impulse relay normally connected to said incoming circuit, an impulse transmitting device for transn'iitting impulses over said incoming circuit to directively operate said impulse relay, a second relay under the control of said impulse relay, electron'iagnetic means inductively connected to said second relay and responsive to impulses repeated thereby, a change-over device for determining the sequence of operation of said primary and secondary motor magnets, means for rendering interconnected circuits busy. a test relay for preventing the seizure of a busy outgoing circuit by said automatic switch, a circuit for the primary motor magnet serially including said change-over device. said circuit being controlled at said electromagnetic means and a circuit, for said secondary magnet controlled by said testing means, by said change-over device and said electromagnetic means.

i 7. in an automatic telephone system, an incoming circuit. a plurality of outgoing circuits, an automatic switch for interconnecting sald incoming circuit with any of said. outgoing circuits, oft normal contacts for said automatic switch, a primary motor magnet and a secondary motor magnetfor operating said automatic switch, an impulse relay normally connected to said incoming circuit, an impulse transmitting device for transmitting impulses over said incoming circuit to directively operate said impulse relay, a second relay operating under the control of said impulse relay, electromagnetic means inductively connected to said second relay and responsive to impulses re peated thereby, a change-over de ice for determining the sequen e of operation of said primary and secondary motor magnets, means For rendering interconnected circuits busy, a test relay for preventing the seizure of a busy outgoing circuit by said automatic switch, a circuit for the primary motor magnet serially including said changeover device and said oil normal contacts, said circuit being controlled at said electromagnetic means, and a circuit. for said secondary magnet controlled by said testing means. by said change-over device and by said elec tromagnetic means.

8. In an automatic telephone system, an incoming circuit, a plurality ofoutgoing cir ill cults, an automatic switch for interconnecting said incoming circuit with any of said outgoing circuits, a primary motor magnet and a secondary motor magnet for operating said automatic switch, normally closed and normally open oil-normal contacts for said automatic switch, an impulse relayt normally connected to said incoming circuit, an impulse transmitting device for transmitting impulses over said incoming circuit to directively operate said impulse relay, a second relay operating under the control of said impulse relay and responsive to impulses repeated thereby, a change over device for determining the sequence of opera tion of said primary and secondary motor magnets. means for rendering interconnected circuits busy. a test relay ttor preventing the seizure of a busy outgoing circuit by said vice and said electromagnetic means.

9. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for extending said incoming circuit to any of said outgoing circuits. a motor magnet for said automatic switch, an impulse relav normally connected to said incoming circuit, means for transmitting impulses over said incoming circuit to directively operate said impulse relay, a transtorn'ier relay responsive to the operation of said impulse relay, a third relay normally slioi't-ciicuited by and inductively connected to said transformer relay, said third relay being responsive to impulses repeated by said transformer relay, an electromagnetic change-over device for determining the operation of said automatic switch, and a circuit for said motor magnet serially including said electromagnetic changeover device and being controlled by said third relay.

10. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for interconnecting said incoming circuit with any of said outgoing circuits, a motor magnet for IIClVELDQlDg said automatic switch, an impulse relay normally connected to said incoming c rcuit, means for transmitting impulses over said incoming circuit for operating said impulse relay, a transformer relay controlled by said impulse relay, a third relay normally shortcircuited by and inductively connected 'to said transformer relay and responsive to impulses repeated by said :ransformer relay, said third relay being provided with normally open contacts, and a circuit forsaid motor magnet completed at said normally open contacts.

11. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for interconnecting said incoming circuit with any of said outgoing circuits, a motor magnet for advanc'ng said automatic switch, an impulse relay normally connected to said incoming circuit, means for transn'iitting impulses over aid incoming circuit to variably operate said impulse relay, a transformer relay controlled by said impulse relay, a third relay arranged to be controlled by impulses from said transformer relay, said third relay being provided with normally open contacts, a change-over device for controlling the operation of said motor magnet and a circuit for said motor magnet serially including said change-over device and said normally open contacts.

12. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for interconnecting said incoming circuit with any of said outgoing circuits, a motor magnet for advancing said automatic switch, a relay having primary and secondary windings in inductive relation, armature controlled contacts for said relay, means including said incoming circuit for transmitting impulses to the prfinai'y winding of said relay, a second relay, a circuit serially including the winding of said second relay and said secondary winding, means including said armature cont-rolled contacts for short-circuiting the secondary winding of said first relay when said first relay dcenergized, and a circuit for said motor magnet controlled by said second relay.

13. In an automatic telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch for extending said incoming circuit to any of said outgoing circuits, a motor magnet for advancing said automatic switch, an impulse relay normally connected to said incoming circuit, means for transmitting impulses over said incoming circuit to operate said impulse relay, a second relay controlled by said impulse relay to repeat two impulses for each impulse received by said last mentioned relay, means for short-circuiting certain of said repeated impulses and men for controlling and motor magnet in response to certain others of said repeater impulses.

In witness whereof, I hereunto subscribe my name this 14th day of January A. D. 1922.

WIN FRED T. POWELL.

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